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The result of the UNION operation between R1 and R2 is a relation that includes

  • A.All the tuples of R1
  • B.All the tuples of R2
  • C.All the tuples of R1 and R2
  • D.All the tuples of R1 and R2 which have common columns

Answer: C

Correct answer: All the tuples of R1 and R2

Union returns every tuple that appears in either relation, with duplicates removed. It requires the two to be union-compatible: the same number of attributes, with matching domains. The last option describes an intersection or a join, not a union.

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